Western Red Cedar


Thuja plicata heartwood is generally a pinkish salmon to red colour but can also be chocolate brown. The sapwood is narrow and almost white. WR Cedar is dimensionally very stable. Texture is fine but uneven due to the prominent growth rings and the grain is straight.  

Uses and applications: WR Cedar, with its attractive appearance, is suitable for panelling and joinery. However, because the timber is soft it is subject to indentation and therefore should not be put in applications requiring a hard-wearing timber. WR Cedar is ideal for exterior cladding, provided only heartwood is used. 

Physical and Mechanical Properties: WR Cedar is a low density softwood. It is not a structural timber, being considerably weaker than pine.

Galvanised fixings are recommended for exterior uses because unprotected iron nails stain the timber. Alternatives include stainless steel, silicon bronze or copper. Nail holding is poor to medium and annular grooved nails or special fasteners may be required to ensure a strong assembly. 

Not suitable for applications subject to loads or surface abrasion (wear), because of its low density and softness. Subject to surface erosion from exposure to weather. 

WR Cedar is easily worked. Since WR Cedar is very soft there is a risk when dressing it that the cutters may compress the softer earlywood which will later recover to produce a ridged surface. Thus sharp cutters are required. Sanding dust can be very irritant to the breathing passages so a well ventilated workshop is essential.

WR Cedar takes glue, stain and paints well.  

Natural durability: WR Cedar heartwood is not ground durable. It is durable in above-ground exposure conditions and is suitable for exterior applications such as cladding. Sapwood is perishable but is suitable for use indoors.

It is one of our three most highly recommended species for weatherboards!

Board lengths range from 1.8m to 6m

Download Cedar Technical Information Sheet

Botanical Name: Thuja plicata
Other Names: Cedar, Giant Arbor Vitae, Red Cedar
Origin: North America
  • Overview
  • Basic Info
  • Technical


Certifications Available::
Seasoning: Smaller sizes dry easily, larger boards need extra care to prevent internal checking and collapse. Almost no tendencies to warp and check once dry with little swelling or shrinking movement.
Working Qualities: The timber is easily worked, but its brittle nature can cause splintering also its soft character can lead to chip-bruising. Care should be taken when planning and moulding, sharp cutters will also help create a nice finish. Stains and paints well.
Uses: Interior panelling, fine furniture, interior and exterior joinery, weatherboards and cladding.
Price (1-10): 5


Stocked: Yes
Grade Description: Premium Clears No.1 PC1 is the highest grade of Western Red Cedar imported into NZ. It is primarily sourced from the coastal forests of British Columbia, Canada. The grade is generally considered a ‘clears’ grade with a small number of allowable knots and defects per metre. The timber is visually graded so up to 5% may be considered out of grade or below grade. End splits are a characteristic of the drying process. End splits are allowable up to the length of the width of the profile. I.e. for an ex 200mm profile an end split up to 200mm is within grade. These natural imperfections are generally docked out by the user, but this will depend upon the end use requirements. It is the responsibility of the Builder/Installer to ensure the grade being used is compliant to the required building code or consent issuing authority requirements. Refer to compliance section below. Premium Clears No.2 PC2 is similar to PC1 except there is a higher percentage of knots and defects allowed per metre. These natural imperfections are generally docked out by the user but this will depend upon the end use requirements. PC2 grade generally means there will be a shorter length spread as a higher number of excluded knots and defects results in a more boards being docked, and therefore percentage of wastage may be higher. Compliance Although every care is taken to ensure the timber in each grade is within the grade specification, it is the responsibility of the Builder/Installer to exclude knots, defects and splits that will not be compliant to the required building code or consent issuing authority requirements. Generally, for external cladding applications, knots that are ‘loose,’ ‘bark-encased’, or liable to fail should be removed. Any knot that contains star-checks and splits that will allow moisture ingression must also be removed. Tight inbound knots that pose no weathertightness risk and that will remain sound for the expected serviceable life of the cladding system may be allowed under current guidelines outlined in the NZ building code, and considered a natural feature of Western Red Cedar.
Photos of Western Red Cedar http://www.timspec.co.nz/News--Info/Image-Gallery-s155205-1110.htm


Primary Suppliers: Western Forest Products
Resource Certification: CSA (which is PEFC)


Durability Above Ground: Durable


Density Air Dry: 380 kg/m3


Shrinkage Radial: 2 %
Shrinkage Tangental: 5 %


Stability Kiln Dry: Very stable
Stability Green: Stable

Mechanical Properties

Janka Hardness: 1.6 kN
Modulus of Rupture: 53 MPa
Modulus of Elasticity: 7.7 GPa
Max Crush Strength: 35 MPa
Strength Group unseasoned: S7
Strength Group Seasoned: SD7
Comp Strength Perp to Grain: 3.4 MPa
Shear Strength Parallel to Grain 5.6 MPa


NZAS lgnitability: 14
NZAS Flame Spread: 10
NZAS Heat Evolved: 9
NZAS Smoke Developed: 4
ASTM Flame Spread: 70
ASTM Smoke Developed: 213

Phone our sales team on (09) 620-0260 or Email us anytime, we'd be happy to help.